Safety paper and process of making the same



Patented Apr. 28, 1925.

UNITED STATES CHARLES FRANK SAMMET, F DALTON, MASSACHUSETTS, ASSIGNQR TOCRANE &

I 1,535,861 PATENT OFFICE." v

COMPANY, or DALTON, mssacnusn'r'rs, A ran'rnnnsnrr'.

SAFETY PAPER AND rnocnss or MAKING HE SAME No Drawing.

To all whom it may concern:

Be it known that I, CHARLES FRANK SAM- MET, a citizen of the UnitedStates, residing at Dalton, in the county of Berkshire, .State ofMassachusetts, have invented certain new and useful Improvements inSafety Paper and Processes of Making the Same, of which'the following isa description.

My invention relates to an improved process for the manufacture ofsafety pa er for checks, notes, bonds, wills and ot er documents, andhas for its object the pro ductionof a paper of such character that anyattempt to obliterate or remove writing, printing or other marks thereonby chemical means will cause a marked change in the appearance or colorof the paper where the chemical has been brought in contact with thesurface, as a result of which changes in the Writing or printing orothermarks will be more apparent and the fraud easily detected.

It will also be understood that the invention is applicable either toplain white or tinted paper, as well asrto paper having surface markin sthereon for the purpose of indicating w en mechanical erasures of thewriting or marking thereon have been made.

In the manufacture of this safety paper by incorporation of theingredients applied thereto in the body of the paper, I make use of anyof the usual well-known processes for the manufacture of paper, and thematerial to be used in the process for making the safety paper and forthe purpose of accomplishing the result, is incorporated in the paper atany desirable stage of the manufactureeither while the paper is in thepulp stage; on the web; or the material 'may be added during the sizingoperation.

The essential feature of the invention con sists in the incorporationtherewith at any desirable stage in the manufacture of the paper of amember of the benzidine group, such as benzidine orits,.homologues,substitution products, derivatives or salts. Of this Iprefer benzidine, ortho-tolidin and orthodianisidine, and I find themost useful to be an insoluble salt of benzidine and of these I )referthe sulphate.

Vhile, as above stated, the safety material may be incorporated with thepaper at any suitable stage in its manufacturethat is, in

Application filed October 31, 1921. Serial at. 511,808.

the pulp, in the web, after or with the sizing-it will also beunderstood that it may be applied as a coating to the otherwise finishedpaper; or,when desired, it may be applied by incorporating it with theink used for marking the paper. I also consider the invention broadenough to include the application of the safety material to the finishedpaper either in the form of. a powder or suspended in a liquid or as asolution. In fact, in a co-pending application Serial No. 511,510,executed of even date herewith, I have set forth a way of applying thematerial to the finished paper by molding the material in the form ofsticks somewhat analogous in size and shape of the well known sticks ofshaving soap, the molding being accomplished under pressure or byincorporating a small amount of binder, such as starch, with thematerial sufficient to hold the particles together. This stick may berubbed over the paper manually with the exertion of slight pressure andthe excess ma terial may then be removed either by blowing or dusting itofl. A sufiicient amount will remain incorporated in the surface of thepaper to produce the desired result.

When the paper is manufactured'by incorporation of the safety materialduring the process of manufacture of such paper, I have foundsubstantially the following proortions give the best results, viz: 100parts y weightof pulp to parts of the benzidine salt, although it willbe understood that these proportions may be varied without departingfrom the spirit of-the invention.

The substances of the class named, and es pecially those substancesmentioned, are discolored upon treatment with ink eradicators, whichusually contain oxidizing agents, the change being due to the oxidizingeffect of the eradicator, although other ingredients thereof may alsoproduce a color change in the safety material. A dirty brown spot isusually produced upon the paper with which they are in contact, whichspot cannot be obliterated by treatment with acids, alkalis,reducingagents or other chemicals.

I have found that the safety substances I propose to use are best usedin the form of insoluble salts, for example, as sulphates, since thecolor of the benzidine or other sulphate or other insoluble salts arepractically unaffected by long exposure to light, while the solublesalts are somewhat darkened by long exposure thereto.

The stain produced by treatment with an oxidizing agent cannot beremoved by treatment with acids or alkalis or reducing agents; however,should a reducing agent be present during the treatment with anoxidizing agent the stain may not appear until the reducing agent hasbeen oxidized. v

I use the variety of tolidin and dianisidine sold as such upon themarket and believe these to have the ortho-structme.

In a co-pendihg application Serial No. 511,809, designated as Case II, Ihave claimed the process of making safety paper and the product itselfhaving diphenylamin incorporated therewith, and the applicationheretofore referred to as relating to the stick of safety material isdesignated as Case III, Serial No. 511,810.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is: e

1. The process of making safety paper which consists in adding to thepaper a material which is a colorless member of the benzidine group orits homologues.

2. The process of making safety paper which consists in adding to thepaper a salt 0% the benzidine group or homologues there- 0 3. Theprocess of making safety paper which consists in adding to the paper aninsoluble salt of benzidine.

4. The process of making safety paper whichconsists in adding to thepaper benzidine sulphate.

5. The process of making safety paper which consists in adding to thepaper benzidine sulphate in substantially the following prop0rtions100parts by weight of pulp to 5 parts by weight of benzidine salt. 6.Paper, having a colorless member of the benzidine group incorporatedtherewith. 7. Paper, having a colorless member of the benzidine groupincorporated therein.

8. Paper, having a salt of a member of the benzidine group incorporatedtherewith. 9. Paper, having a salt of a member of the benzidine groupincorporated therein.

10. Paper, having an insoluble salt of a member of the benzidine groupincorporated therewith.

11. Paper, having an insoluble salt of a member of the benzidine groupincorporated therein.

. 12. Paper, having an insoluble compound of a member of the benzidinegroup incorporated therewith.

13. Paper, having an insoluble compound of a member of the benzidinegroup incorporated therein.

14. Paper, having a sulphate of a member of the benzidine groupincorporated therewith.

15. Paper, having a sulphate of a mem ber of the benzidine groupincorporated therein.

16. Paper, having benzidine incorporated therewith.

17. Paper, having benzidine incorporated therein.

18. Paper, having a salt of benzidine incorporated therewith.

19. Paper, having a salt of benzidine incorporated therein.

20. Paper, having an insoluble compound of benzidine incorporatedtherewith.

21. Paper, having an insoluble compound of benzidine incorporatedtherein. I

.22. Paper, having an insoluble salt of benzidine incorporatedtherewith.

23. Paper, having an insoluble salt of benzidine incorporated therein.

24. Paper, having benzidine sulphate incorporated therewith.

25. Paper, having benzidine sulphate incorporated therein.

In testimony whereof, I afiix my signature.

CHARLES FRANK SAMMET.

